Fluid analysis control



1965 H. HELLER ETAL 3,

FLUID ANALYSIS CONTROL Filed May 24, 1961 4 Sheets-Sheet 1 2Q PROGRAMMER 4e VA LVE Bacon 01.12 50 PuLsEo RELAY Posmoman 3],, SYNC /|36 DC PuLsz- Smczow To Esconuzralk rz ATION A SIGNAL LOOP S C ES 34 58-. SIGNAL.

ATTENUATION Nm-wozx STE PPING RELAY REGULATE 0 44 Power: 50 m IN V EN TORS. HERBERT HELL E4? HENRY J. 7' CLAYTON J. 505.942?- acexmvaez 0. ms INA/5 BY 5.424 M. BECKER Aug. 10, 1965 H. HELLER ETAL.

FLUID ANALYSIS CONTROL 4 Sheets-Sheet 2 Filed May 24, 1961 BEC HO AC HOAC COHSTA NT VOLTAGE.

IIOAC NEUTRAL Aug. 10, 1965 Filed May 24, 1961 FLUID ANALYSIS CONTROL 4 Sheets-Sheet 3 INVENTOR HERBERT HELLER HENRY J. THEN CLAYTON J. BOJJflE7' BY HLEXANDEI? C. "SIN/V68 EHEL ['7- BBC/(51?.

Aug. 10, 1965 H. HELLER ETAL, 3,399,338

FLUID ANALYSIS CONTROL F'iled May 24, 1961 4 Sheets-Sheet 4 i v-ra/zur United States Patent 3,l9,333 FLUTE ANALYSIS CONTROL Herbert Heller and Henry 3. Then, Pittsburgh, Clayton J. Bossart, Monrceville, Alexander (I. Mclnnes, Export, and Earl M. Becker, Pittsburgh, Pa, assignors t0 Mine 7 Safety Appliance Company, Pittsburgh, Pa, 21 corporation of Pennsylvania Filed May 24, 1961, Ser. No. 112,446 2 Claims. (El. 7323.1)

This invention pertains to fluid analysis and particularly to the means for analyzing gases and using gas chromatography principles.

The invention pertains to fluid chromatography of either the adsorption type or the gas-liquid partition type. Merely for the purposes of illustration, this invention will be described in connection with adsorption chromatography wherein a column or columns contain appropriate adsorbents, usually in granular form, to separate various constituents of a gas sample or samples. The sample is introduced to the column in a carrier gas stream continuously flowing through the column. Various components of the gas sample are separated by the process of selective adsorption and desorption so that the separated constituents issue from the end of the column in sequent-ial order corresponding to their volatility, weight or property affecting the degree of adsorption on the packing material in the column. conventionally, the separated gases emerge from the column and then pass through a suitable detector element which in some known way measures the property of the gas indicative of the character and amount present.

Prior art devices have not been fully satisfactory in that the instrument which programs or times the sequence of events lacks precisions and flexibility. These devices, also require improvement in the valving and valve control used in the chromatographic columns. In addition, experience has shown that previous analyzers were not altogether stable because of uneven temperature conditions. arrangement and operation.

It is an object of this invention to overcome the aforesaid disadvantages by providing an analyzer which is precise and flexible in its operations, stable insofar as internal and ambient temperatures are concerned, and permits the use of at leat two columns to be operated independently or simultaneously in either direction with the option of using the two columns in series or parallel.

The invention will be clearly understood with reference to the following description taken in conjuction with the accompanying drawings, in which:

FIG. 1 shows a schematic and diagrammatic wiring circuit of this invention;

FIG. 2 is a schematic diagram showing the pulsed relay and synchronization circuit of FIG. 1;

FIG. 3 shows the programmer schematically;

FIG. 4 is a fragmentary view of the tape used in the programmer;

FIG. 5 is a perspective view, partially exploded, of the chromatographic valves and the valve controller;

FIG 6 is a schematic flow diagram of the analysis unit;

FIG. 7 is a schematic wiring diagram for the valve controller of FIG. 5;

FIG. 8 is a vertical sectional view of the analyzer housing; and

FIGS. 9 and 10 show the high and low temperature control circuits.

Referring briefly to FIG. 1, a programmer sets up a program of gas analysis for the chromatograph having therein a detector 24 and valve positioner 23. The signal or pulse produced by programmer 20 is fed into a Moreover, such analyzers are restricted in column pulsed relay 3t) and synchronization circuit 31, the output D.C. pulse of which is fed into the DC. stepping relay 34. This relay is a four level, four interrupter contact type with 26 steps (the contacts and some of the steps are not shown). Relay 34 services indicator 36 which enunciates the functions of the levels of relay 34, valve positioner 2S, synchronization circuit 31, signal attenuation network 38, recorder 4t) and fine zero servo 42. Each signal produced by the pulsed relay 30 causes the four levels of relay 34 to advance one step. The synchronization pulse initiated by the programmer 20 as a result of portion 27 (FIG. 4) is sensed by synchronization circuit 31 to cause the relay 34 to return to its number one contacts by way of synchronizing signal fed to level 34A. The long pulse produced by the wide portion 27 is sensed by a time delay relay 31A (FIG. 2) which feeds the synchronizing signal to relay 34 to resent all relay levels. if, however, all levels are at their number one contacts, the synchronizing pulse has no effect on relay 34. Level 34B produces a chart drive signal received by recorder ill. Simultaneously, level 34C produces a signal to indicator 36 and valve positioner 28, and level 34]) produces three signals; one to actuate valve positioner 28, one received by signal attenuation network 38 to accomplish the proper attenuation and one which feeds servo 4,2 for adjusting fine zero of detector 24. This fine zero can be manually adjusted by knob 45. Regulated power supply 44 supplies power to detector 24. Push button 46 permits the system to be operated manually if the programmer 2t is not used. All of these components coact to manipulate the chromatograph in a predetermined fashion to effect gas analysis.

FIG. 3 shows the programmer or sequence timer 20 comprising a tape or film 21, such as, a 16 millimeter film. This tape is threaded around smooth spools 23 and a sprocket 23A in a continuous loop. One of the spools 23 rides in a slot 25 for adjusting the tightness of the tape around the spools. As is best seen in FIG. 4-, tape 21 contains sprocket holes 26 for engagement with sprocket 23A. Numeral 2'7 represents a wide blanked or darkened portion which interrupts the light radiated by lamp 29 to cause a synchronization DC. pulse to register in photoelectric receiver 29A to close relay 30B. Numeral 32 refers to marks placed on the tape to produce pulses as just mentioned. These marks are placed at selected intervals by pencil or any other suitable marking means so that a present programming is available for the chromatograph. Time division marks 33 act as guides for marking the tape.

The basis for sequence timing is the passing of tape 21 between the photoelectric transmitter and receiver at a sequence speed. Each mark on the film will cause the receiver to feed a signal to pulsed relay 3% and synchronization circuit 31 which in turn advances the stepping relay 34. The tape is graduated on a time basis, one second divisions, for example, and the length is cut to correspond to the analysis time or a multiple of the analysis time required. As the stepping relay contacts do not advance until the end of the marking, the thickness of the mark is of no consequence and the timing is determined by the placement of the trailing edge of the mark. Portion 27 provides a long pulse that is sensed by relay 31A of circuit 31 (see FIG. 2) to reset the stepping relay 34. As this relay should be at its first step at this time of the cycle, portion 27 will monitor synchronization. The system will be accurate to the extent of automatically synchronizing Within one film loop during start-up or after a momentary power failure. The light beam intensity of lamp 29 is adjusted to provide proper sensitivity.

FIG. 2 schematically shows specific details of the pulsed relay and synchronization circuit. When, for example, a

programmed mark 32 passes between light source 29 and receiver 29A, the resistance of 29A is increased thereby increasing the voltage on the grid of gaseous tube SllA. Increased grid voltage causes the tube to conduct current to energize relay coil Still closing normally open relay contacts 3M) and Still) to permit DC. voltage to energize coil 234T of stepping relay 34 through conductor 13%. Energizing coil 324T opens normally closed switch 34V and mechanically prepares sliding contacts of levels 34A, 34B, 34C and. 54D for subsequent sliding advancement. When opened, switch 34V interrupts the power supply through conductor TS-d to relay 34 to prevent arcing when the contacts of the levels advance. The mark having been passed, the tube and relay revert to original operating conditions, and DC. voltage is removed from coil 34T. it is characteristic of relay 34 that, when coil 34T is eenergized, levels MA, 34B, 34C and 34D each advances one step in its sequence with the same step number for each level. it will be noted that the closing of contacts 349C and Elli) conducts current to heater 311) of thermal relay 31A. Since, however, mark 32?, is not wide enough, coil 3'93 is deenergized before normal- 1y open bimetal switch 31B is closed.

When an abnormally long precalibrated mark, such as mark 27 (FIG. 4), passes between the source 29 and receiver 29A, the operation is the same as described above except that coil EilB is energized for a much longer period of time. This long energization permits heater 31D to close bimetal switch 318 and pass current to coil 324T through conductor llfld. When the mark 27 passes, coils 30B and 341" will be deencrgized and relay 3 will a vance one step. Should this step be other than step one of level 34A, voltage will be transferred through conductor 13$, switch 34V, the sliding contact of level 34A, conductor 13%, closed switch 312 and conductor 134 to energize coil MT. At this time, coil 374T will open switch 34V thus becoming self-interrupted. This interruption will advance relay 34 one step. The process is repeated until step one of 34A is reached. Since step one does not provide a closed circuit, it is necessary to energize coil 303 by another mark to actuate relay Ed.

The efiect of a program marking may be simulated by closing pushbutton When switch 46 is depressed, resistance 36A is placed in parallel with resistance StlE. The parallel resistance of this combination is lowered so that the voltage across 22A and the grid of tube 39A is increased enough to actuate the tube and relay 3013 as previously described.

Thusly, it is seen that the programming by programmer 20 is extremely accurate, flexible and easily adapted to provide any combination of analysis time and sequence as required.

Looking now at FIG. 5, valve positioner 28 comprises a conventional reversible motor which drives cam 5?. and driver 53 through gear box 52 and shaft 54. Driver 53 drives cam follower 55 which actuatcs sprockets 56 and 57. The sprockets and driver are commonly known as a Geneva movement indicated by numeral es. Briefly, when follower 55 rotates counterclockwise through 180, it engages sprocket or cam slot 5 5A to effect 99 clockwise rotation of sprocket 56. Similarly, 180 clockwise rotation of follower 55 slot 56A to take it back to its original position through a 90 rotation. Follower 55 engages slot 57A in the same manner. Although sprockets 56 and 57 each have four cam slots, only one of each is numbered. Sprockets 56 and 57 actuate valves 61 and 62 which provide the required fluid flow in the chromatographic columns as and d6 schematically shown in FIG. 6. Cam 51 (FIGS. 5 and 7) actuates switches 75A, 768, 79C and ND. Switches WA and 7th) through conductors 72 and '73 determine the direction in which the motor 50 will rotate depending upon which motor winding is powered through the motor relay circuit 50A between motor 55 and levels 34]) and of relay 3d. Power on conductor 72 drives motor 55 counterclockwise in step one of level and clockwise in step three. Power on conductor 73 drives motor till clockwise in step two and counterclockwise in step four. Switches 7llB and MD provide a means for synchronizing the position valves dil and 63.

Referring to FIG. 7, the arrows V, W, X and Y indicate direction and extent of cam rotation. When the motion of cam 51 is in the direction of arrow V, motor 55 turns in a counterclockwise direction. Similarly, when the cam moves in the direction of arrows W, X or Y, motor 5% rotates in clockwise, clockwise, or counterclockwise direction, respectively. Switches A and 7tlC are normally biased closed and are opened by lobe 51A. Switches 79B and 'TED are normally biased open and are closed by lobe 51A. To actuate cam 51 in the direction of arrow V, step one on level 34D of relay 34 powers conductor 72 through switch 70C. This circuit to motor 59 is completed through contact 154 or" relay 3159 closed upon contact 156 and motor conductor 57 to rotate the motor in a counterclockwise direction. This motion is completed when lobe 51A opens switch W3C. During this rotation of cam 51, latching relay 74. is energized by way of switch 769]) when lobe 51A closes it to close contacts and 77. To actuate cam 51 in the direction of arrow W, step two on level 341) powers conductor 73 through contacts 75, 77 and switch 'iilA which is now closed. This circuit to motor 54) is completed through contact 1531 of relay 1569 closed upon contact 152 and motor conductor 158 to rotate the motor in a clockwise direction. This motion is completed when lobe 53A opens switch 7tlA. The direction noted by arrow X is accomplished by step three of level 34D supplying power to conductor '72 through switch 79C. Simultaneously with the movement of the sliding contact of level MD to step three, the sliding contact of level 343 also is at its step three energizing relay 15d to close contacts 151 upon 1535 and 15% upon 155. Thus, conductor 72 is connected to motor 50 through closed contacts 154, and conductor 158 to rotate the motor clockwise. During this rotation of cam 51, latching relay 74 by way of 70B closes contacts 75 and 76. Similarly, the direction indicated by arrow Y is accomplished by position four of level 34D supplying power to conductor 73 through contacts 75, 76 and switch 70A. Since step four of level 34C is still holding relay 159, conductor '73 is connected to motor 50 through con- ;tacts 151i, 153 and conductor 157 to rotate the motor counterclockwise. These last two motions are completed in the same manner mentioned above for the first two. The change in direction of motor 50 positions valves 61 and 62. Directions V and W permit valve 61 to be driven first in a clockwise direction and then in a counterclockwise direction. Directions X and Y permit valve 62 to be driven first in a counterclockwise direction and then in a clockwise direction. It is to be noted that cam 51, and valves 62 and 2 are correlated in a manner whereby, if directions of the cam are unintentionally missed for one reason or another, the valves will be placed in their original positions at the start of every sequence. For example, after step one of level MD has effected the first movement of valve 61, the only signal that could cause motor 5% to rotate is one resulting from step two. Steps one and three would be inoperative since switch 700 would be open and step four would be inoperative because of opened contacts '75 and 76. When step two has effected movement completion of valve 61, the only signals that are operationalare those resulting from steps one and three. Step four will not cause operation due to open contacts 75 and 76. The other phases of valve rotation are similarly governed. Thus, valves 61 and 62 will always operate in the proper sequence.

One example of a typical flow schemecan best be seen by referring to FIG. 6. The initial position of valve 61 is represented by the dotted line position and the initial position of valve 62 is represented by the solid line position. Carrier fluid, for example, helium, enters inlet 81,

through ports A and F of valve 61, thence to column 65, to ports M, N, I and J of valve 62, to column 66, to ports K and L (valve 62) and finally to outlet 81A and detector cell 24. This detector cell, as an example, is a conventional thermal conductivity cell. Sample gas, for example, hydrocarbons such as methane, ethane and propane, enters inlet 83 and passes through ports G, C, B, E, D and H of valve 61 to outlet 83A. The initial step of the cycle is the actuation of valve 61 to the solid line position by rotation in the V direction and extent. Sample gas is now diverted through sample inlet 83, ports G and H to outlet 83A. Helium enters inlet 81, ports A, B, C, D, E and F to column 65, thus sweeping a known volume of sample gas from sample conduit BCDE into column 65. Valve 62, in the meantime, remains in the solid line position, so that columns 65 and 66 are in a series flow path. After a suitable time period, long enough to insure complete flushing of the sample conduit, BCDE, valve 61 is returned to the dotted line position by rotation in the W directionand extent, resuming sample gas flow from inlet 83 through ports G, C, B, E, D and H to outlet 33A. Helium flow is now direct from inlet 81, through ports A and F to column 65. When the light components in the sample gas have entered column 66, but not exited therefrom, valve 62 may be actuated to the dotted line position by rotation in the X direction and extent, trapping column 66, between ports I and K of valve 62, in a non-flow condition. The heavy components eluting from column 65 may then pass through ports M and O, a suitable restrictor, ports P, N, I and L to outlet 81A to detector 24, thus bypassing column 66.

When the heavy components have been eluted through detector 24, valve 62 may be actuated to the solid line position by rotation in the Y direction and extent, resuming series flow of helium through columns 65 and 66. The light components of the sample are now eluted from column 66 through ports K and L, outlet 81A, and detector 24. Valves 61 and 62 are in position to begin a new analytical cycle. Many combinations of valve actuation may be accomplished by modifications of the sprocket drive mechanism and stepping relay circuitry for applicability to other flow schemes.

The analysis unit or chromatograph is housed in a Grouse-Hinds type EPC explosionproof condulet or housing 85 as shown in FIG. 8. This type of structure facilitates both maintenance and thermostating of the assembly. Housing 85 comprises an outer metallic cylinder 78 and intermediate metallic cylinder 80 having an upper opening 82 and lower opening 83. Inner metallic cylinder 86 is of the Dewar flask type having a bottom member 88 forming chamber 87. Mandrel 90 is fabricated from a heavy aluminum mass and is shaped as a truncated cone. Chromatographic columns 65 and 66 of metallic tube are Wrapped around mandrel 90, and are connected to valves 61, 62 and detector 24. The fluids enter the valves and into columns 65 and 66 to pass into detector cell 24, and then are vented. The columns, valves, detector cell and gas conduit are merely shown schematically for ease of illustration. A mandrel heater 92 is imbedded in the mandrel 90 for purposes explained later. A thermistor 94 is located at opening 82, and bimetal thermostats 95 and 96 are located in the mandrel. Motor driven fan 98 is located at the bottom of cylinder 78, and an electric heater 99 is positioned around the lower end of cylinder 80.

Two temperature zones are set up by the above-described structure. Chamber 87 constitutes the high temperature zone. This zone contains the adsorption columns, valves, geneva movement, and the thermal conductivity detector cell. A 3000 Watt heater 92 is employed as a source of heat. Noting FIGS. 8 and 9, the operation is explained when a fast warmup of the apparatus is desired. Depressing push button 1015 applies 110 v. A.C. directly to heater 92 through conductors 101, switch 104 and conductor 105. Switch 104 is closed by the actuation of relay 106. Relay 118 opens switch 167 and closes contact 109 with 110. This heat is ap plied until the temperature level of bimetal low temperature thermostat is reached. This temperature is several degrees below the operating temperature selected for the chromatographic columns. During this time safety thermostat 96 is closed and relay 113 has closed switches 114 and 116.

When the above mentioned temperature level has been reached to open thermostat 05, and since safety high temperature thermostat 26 is closed, relay 118 closes switch 107 and opens contacts 109 and to provide power through a 32 volt step-down transformer 117. If the temperature exceeds 500 F., for example, thermostat 96 will open cutting off all power to heater.92.

The low temperature zone is located in the space designated as 120 (FIG. 8). This zone must be under thermal control to provide constant heat flow from chamber or zone 87. As long as heat flow is constant, temperatures can be made stable by even supply of heat to match the flow from the chamber. Air is directed through the low temperature zone 120 by means of a motor driven fan 98. This air is warmed when required by a 450 watt heater 99 which is governed by a balanced thermistor bridge control unit 122. A glass encased thermistor sensing element 94 forms one side of the bridge and senses temperature changes as small as 03 F. As thermal equilibrium exists between the high and low temperature zone, the temperature at this point should not vary very much, but as the ambient temperature varies, the thermistor will sense this change to heat up the low temperature zone to maintain a stable temperature within the high temperature zone. Indicating light 124 is merely a visual means to determine whether the heater is operating. Thusly, it is readily seen that stable temperature is provided throughout the main portion of the analyzer so as to insure sensitivity and stableness in the analyzer.

Detector 24 (FIGS. 1 and 8) quantitatively detects the gases separated during passage through columns 65 and 66. The gases leaving outlet 81A of column 66 are passed through a thermal conductivity cell in detector 24 producing signals characteristic of the gases. These signals are passed through signal attenuation network 38 to recorder 40 which indicates the amount and kind of gases. If the signals are of such magnitude as not to be compatible with the scale of recorder 40, network 38 will attenuate the signals to properly record them. The magnitude of these signals are predetermined by calibration with known samples of gases so that the proper network 38 can be selected to match the type recorder 40 desired. The detector signals are attenuated at programmed in tervals determined by the number of relay steps selected on level 34D of relay 34. Thus, the manner of marking programmer 20 determines the sequence of signal attenuation relative to the sequence of operation of all other analyzer components.

A brief description of the manner in which the analyzer operates will now be stated. After the housing 75 has been properly prepared temperature-wise and tape 21 marked to provide the desired programming, the gases to be measured are connected to the inlet of valve 61. Tape 21 is started and the marks thereon produce signals responded to by pulsed relay 30 and synchronization circuit 31 to actuate the four levels of stepping relay 34. Level 34A further forms a loop with circuit 31 for resetting all levels of the relay to the starting position when a longer signal than normal is produced by the programmer. As the levels operate in sequence, valves 61 and 62 are rotated in the predetermined sequence by geneva movement 60 driven by reversible motor 50. The direction and extent in which this motor is operated is determined by cam 51 and the attendant circuits. Thus, the gases flow through columns 65 and 66 in response to the rotation of valves 61 and 62. The gases leaving column 66 flow through detector 24, the signals from which are be practiced otherwise than as specifically illustrated and described.

We claim:

1. A device for fluid analysis comprising at least one chromatographic column adapted to contain sample and carrier fluids, valve means connected to said column and selectively processing the sample and carrier fluids relative to each other for the separation thereof, a reversible motor and driving means connected to said valve means,

circuit means connected to said driving means and motor for rotating said motor bidirectional, relay means connected to and sequentially operating said circuit means, a programmer having marked means producing output signals, receiving means electrically connected between said programmer and relay means, said receiving means conducting said signals from said programmer to said relay means to operate said relay means in a sequence predetermined by said marked means, said circuit means including switch means operatively associated with said driving means and responding to the direction of rotation of said motor, and said switch means maintaining the direction of rotation of said motor in accordance with the sequence predetermined by said marked means.

2. A device for fluid analysis comprising at least one chromatographic column adapted to contain sample and carrier fluids, valve means connected to said column and selectively processing the sample and carrier fluids relative to each other for the separation thereof, a Geneva movement connected to said valve means, a reversible motor and rotatable driving means connected to said movement, circuit means connected to said driving means and motor for rotating said motor bidirectional, relay means connected to and sequentially operating said circuit means, a programmer having marked means producing output signals, receiving means electrically connected between said programmer and relay means, said receiving means conducting said signals from said programmer to said relay means to operate said relay means in a sequence predetermined by said marked means, said circuit means including acam connected to said driving means and re 'sponding to the direction of rotation of said motor, and switch means in said circuit means and operated by said cam means for maintaining the direction of rotation of said motor in the sequence predetermined by said marked means.

References Cited by the Examiner UNITED STATES PATENTS 1,962,467 6/34 ShOlkin 250-219 X 1,991,276 2/35 Gebhard 219-19 2,235,287 3/41 Daniels 137-62413 2,656,109 10/53 Lindars 235-132 2,875,606 3/59 Robinson 73-23 2,982,123 5/61 (indred 73-23 3,023,605 3/62 Burk 73-23 3,026,712 3/62 Atwood et a1 73-23 OTHER REFERENCES Article: Gas Chromatography, by Dimbat et al., published in Analytical Chemistry, vol. 28, N0. 3, March 1956,

5 pages 290-295.

REHARD o. UErssER, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3, 199,338 August 10, 1965 Herbert Heller et al.

corrected below.

Column 2, line 17, for "resent" read reset line 47, for "present" read preset column 4, line 55, for "62", first occurrence, read 61 Signed and sealed this 15th day of March 1966.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD]. BRENNER Attesting Officer Commissioner of Patents 

1. A DEVICE FOR FLUID ANALYSIS COMPRISING AT LEAST ONE CHROMATOGRAPHIC COLUMN ADAPTED TO CONTAIN SAMPLE AND CARRIER FLUIDS, VALVE MEANS CONNECTED TO SAID COLUMN AND SELECTIVELY PROCESSING THE SAMPLE AND CARRIER FLUIDS RELATIVE TO EACH OTHER FOR THE SEPARATION THEREOF, A REVERSIBLE MOTOR AND DRIVING MEANS CONNECTED TO SAID VALVE MEANS, CIRCUIT MEANS CONNECTED TO SAID DRIVING MEANS AND MOTOR FOR ROTATING SAID MOTOR BIDIRECTIONA, RELAY MEANS CONNECTED TO AND SEQUENTIALLY OPEATING SAID CIRCUIT MEANS, A PROGRAMMER HAVING MARKED MEANS PRODUCING OUTPUT SIGNALS, RECEIVING MEANS ELECTRICALLY CONNECTED BETWEEN SAID PROGRAMMER AND RELAY MEANS, SAID RECEIVING MEANS CONDUCTING SAID SIGNALS FROM SAID PROGRAMMER TO SAID RELAY MEANS TO OPERATE SAID RELAY MEANS IN A SEQUENCE PREDETERMINED BY SAID MARKED MEANS, SAID CIRCUIT MEANS INCLUDING SWITCH MEANS OPERATIVELY ASSOCIATED WITH SAID DRIVING MEANS AND RESPONDING TO THE DIRECTION OF ROTATION OF SAID MOTOR, AND SAID SWITCH MEANS MAINTAINING THE DIRECTION OF ROTATION OF SAID MOTOR IN ACCORDANCE WITH THE SEQUENCE PREDETERMINED BY SAID MARKED MEANS. 